Voltage divider circuit

ilan1 said:

Sparkfun electronics sells this breadboard power supply:

https://www.electro-tech-online.com/custompdfs/2006/02/Breadboard-PowerSupply-v2-1.pdf

that is switchable between 5V and 3.3V. Could somebody clue me
in on exactly how the equations in the voltage divider in the above
schematic gives 3.3V and 5V?

I apologize for my abject ignorance!

Ilan

Click to expand...

ilan1 said:

Did you figure this out from the LM317 data sheet or is there
some general principle here?

Ilan

Click to expand...